Such a positioning aid for magnetic devices used for positioning a shuttering means is known e.g. from EP 0 842 339. The magnetic device consists here of a permanent magnet accommodated in a retaining device. The retaining device is integrated in shuttering parts of the shuttering system and is provided with a lift-off bow which extends over the magnet from one side to the other and which rests on the shuttering support. A spring, which forms the support unit and which applies the lifting force to the magnet, is located between the retaining device and the magnetic device at a position above said magnetic device. At the position of use, the magnet is in contact with the ferromagnetic shuttering support. Due to the holding force of the magnet on the shuttering support, a displacement of the magnet is prevented so that the magnet can be used for positioning the shuttering parts on the shuttering support. The holding force of the magnet overcomes the lifting force of the spring. If the magnet is to be displaced, the magnet is lifted off from the shuttering support by means of a lifting screw. As soon as the magnet is spaced apart from the shuttering support, the holding force applied by the magnet to the shuttering support decreases strongly. At the position of non-use, i.e. in the raised condition of the magnet, the lifting force of the spring is dimensioned such that it overcomes the residual holding force between the magnet and the shuttering support and the weight of the magnet itself, so that the magnet will remain at the position of non-use. The positioning aid can then be displaced to a new site. For fixing the positioning aid to the shuttering support, the magnet is forced towards the shuttering support, until the holding force and the weight of the magnet overcome the lifting force of the spring and the magnet moves automatically into contact with the shuttering support. The force for returning the magnet from its position of non-use to the position of use can be applied e.g. by a blow on the retaining device.
The known positioning aid proves to entail rather a high expenditure, with regard to space requirements as well as with regard to production costs. In addition, it cannot be used in a flexible manner, since the field of use is determined by the magnet provided. If finer contours are to be delimited on the shuttering support by the shuttering elements, or if strong holding forces are required for comparatively large shuttering elements, it is often impossible to use the known positioning aids.
It is therefore the object of the present invention to provide an economy-priced solution for positioning aids, which can be used universally.